Properties of Tannin-Glyoxal Resins Prepared from Lyophilized and Condensed Tannin

Abstract

The main focus of this study was to prepare a thermoset adhesive using green way from two bio-product derivatives i.e., namely: condensed tannin (CT) and lyophilized tannin (LT) from grape pomace, which acquired from wine industries. Firstly, the obtained tannins were isolated and characterized especially by their thermal properties of the isolated tannin fractions which have been investigated in detail. Then, two adhesive resins were prepared using the isolated tannins with the glyoxal as cross-linking agents were employed to produce tannin-glyoxal resin. The evolution of the viscosity during the curing process of Resin-TanninLyophilize-Glyoxal (RTLG) and Resin-Tannin-Condensed-Glyoxal (RTCG) was studied. The influence of the main gelation conditions such as temperature, pH and curing agent type on the gelation time was studied and discussed. Keywords:

Integration of Wnt-inhibitory activity and structural novelty scoring results to uncover novel bioactive natural products: new Bicyclo[3.3.1]non-3-ene-2,9-diones from the leaves of Hymenocardia punctata

“…From a biosynthetic point of view, the new compounds isolated from H. punctata may have been formed by rearrangement of an 8-prenylflavane as suggested for acutifolin A, tazettone A, and tazettone B ( Figure 7 ). A similar rearrangement occurs also when catechin is subjected to basic conditions, forming catechinic acid ( Sears et al, 1974 ; Ibrahim et al, 2007 ; Khiari et al, 2017 ). The extraction process was under neutral conditions, which is an indication of the authenticity of the compounds.…”

“…No. when catechin is subjected to basic conditions, forming catechinic acid (Sears et al, 1974;Ibrahim et al, 2007;Khiari et al, 2017). The extraction process was under neutral conditions, which is an indication of the authenticity of the compounds.…”

Bio-Based Tannin Foams: Comparing Their Physical and Thermal Response to Polyurethane Foams in Lightweight Sandwich Panels

“…The thermogravimetric analysis revealing the thermal degradation behavior of the produced materials is depicted in Figure 6. The TA foam shows a mild degradation-around 13%-until 300 • C, followed by a substantial material loss of approximately 60% of the mass until 550 • C. The initial mass loss event primarily results from moisture evaporation and partial degradation of low molecular weight compounds from tannin extract, such as simple sugars, phenol, and monomers [45]. Within the range of 300-500 • C, two main peaks of degradation are observed: the first at 442.20 • C and the other at 479 • C. These peaks correspond to the degradation of polyphenolic materials of the tannin extract [46], along with the breaking of C-C bonds and the complete breakdown of pyrolysis residual products from carbohydrates like glucose, mannose, and xylose [47,48].…”

Tannins: Extraction from Plants

“…Finally, precipitated tannins were obtained at 8000 rpm for 15 minutes by centrifugation. Yield of extraction is higher than treatment of grape pomace by a solution of hydroxide sodium 5% (w/w) [29]. Maceration is similar to infusion method by which the materials are soaked in cold or boiling water for a short time [31].…”